1. Field of the Invention
The present invention relates to methods for manufacturing field emission electron source and, more particularly, to a method for manufacturing a carbon nanotube (CNT) field emission electron source.
2. Description of Related Art
It has been well known that carbon nanotubes (CNTs) are ideal for use as electron emitters of field emission electron source. Generally, a typical CNT field emission electron source includes a substrate and CNTs as electron-emitters formed on the substrate. Methods for forming CNTs on the substrate include mechanical methods and in-situ growth methods.
In the mechanical method, CNTs are preformed and then moved into contact with the substrate using atomic force microscopy. The CNTs are attached to the substrate using conductive adhesive. The advantage of the mechanical method is that the process is simple. However, since CNTs are so small, they are not easy to manipulate and efficiency is low. Also, the CNTs are attached to the substrate by adhesive and this tends to decrease the field emission of the CNTs.
In the in-situ growth method a catalyst layer is first applied onto the substrate and CNTs are formed using a process selected from the group consisting of CVD (chemical vapor deposition), arc discharge, and laser evaporation. In-situ growth creates a high level of contact between the CNTs and the substrate, however, bond strength of the CNTs to the substrate is weak. When the field emission electron source is used, the CNTs may easily become detached from the substrate, and the field emission electron source may be damaged as a result.
What is needed, therefore, is to provide a method for manufacturing CNT field emission electron sources in which the above problems are eliminated or at least alleviated.